A method for producing a molecular film by coating the surface of a glass or the like having active hydrogen atoms on its surface with chlorosilane-based compounds having chlorosilyl groups at the end of the molecules comprising alkyl groups or fluoroalkyl groups so as to form covalent bonds by a dehydrochlorination reaction already has been proposed.
In the prior art, a substrate is dipped into a coating solution containing chlorosilane-based compounds to form a molecular film, as disclosed in Japanese Laid-Open Patent Publication No. 1-70917 and EP 0492545A. Another example of the proposed methods is to contact the chlorosilane-based compounds in a vapor phase onto the surface of a substrate for effecting a reaction.
However, the conventional dip method is excellent in the case where a film is to be formed not on a flat plate, but instead on a rough surface, because the liquid reacts along the rough surface, so that a film can be formed along the surface of the unusual shaped object. On the other hand, this method requires a large amount of the liquid for dipping and a troublesome operation of putting in and withdrawing the substrate, which takes a long time. Consequently, this method adversely results in a high cost. Furthermore, since the chlorosilane-based compounds readily react with water, the pot life is short. In addition, in the dip method, the chlorosilane-based compounds are in contact with the entire substrate and a reaction is effected all over the surface of the substrate. Therefore, this method is disadvantageous in the case where a prescribed portion is not desired to be coated with the chlorosilane-based compounds.
Furthermore, a method of contacting the chlorosilane-based compound in a vapor phase with the surface of the substrate for effecting a reaction is disadvantageous in that it is difficult to form a molecular film uniformly.